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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
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322 Posts
Discussion Starter #1
I bought this car used over a year ago and it had starting g problems then, with "service theft system" msg. I finally traced it down to corrosion on the hot wire at the data link connector. Now its doing it again with 2 new codes, like torque pull or smtng, one I remember is p0700. If I leave key on long enough it'll like "click n whirr", then it'll start. It did it at a repair shop the other day and they said it was the body control module, when they heard the clicking behind the radio when the key was turned. He jumped the starter relay, and after cranking for a bit it jumped back to life. Any ideas? P1000 radio, p0700 and can't rmbr the 3 others. Been fine for over a whole year. Thanks for any help, this is my daily driver need it running.
 

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2007 CTS 3.6 >131k miles
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701 Posts
I have only seen p0700 one time. In that case a transmission connection had degraded to the point that it had intermittent conductivity and a little dielectric grease on the terminals cleared it up. I have a hunch that's what is going on with your car, or broken wires, etc. The hard part is deciding where to look first. I would probably start under the dash, given that you may have an ignition switch/security issue. Also check the connector to the trans if you can reach it.
 

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5 Posts
had a similar issue - 05CTS would not start. replaced battery and still would not start. after jiggling positive terminal it started so thought it was the cable. while drving to shop i got p700 code. shop later had problems getting started,, left it for a few hours, came back started right up but threw several communication codes. Paid them to do electrical diagnosis and they said bad ECM. shop also reported several communication codes i had not seen before. going to try to replace ECM this weekend. fingers crossed. will report back. there are other threads here about replacing ECM i found helpful.
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
Joined
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322 Posts
Discussion Starter #5
Battery not new, but only 2 yrs old. Still good. Still cranks for a long time. Terminals in good shape. C0243 engine drag malfunction and C 0244 pwm delivered torque are the 2 codes now, that I've never got before. Yea, I agree with all your helpful info. I too, thinks it's either a bad connection somewhere, but where to start, and also am leaning towards a bad pcm. Speaking on pcm, can a used one be just swapped in? With no dealer programming, or anything? I've got a Snap-on 2 way scanner.
 

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2007 CTS 3.6 >131k miles
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701 Posts
The PCM could definitely cause these problems but I would eliminate everything else first. Otherwise the problems will still be there after the new PCM.

The new PCM will have to be programmed with the VIN. Dealer's can do this but I don't know if the procedure is dealer-only. Perhaps others have more knowledge of this.
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
Joined
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322 Posts
Discussion Starter #7
Thanks Ryan. When I first got the car, It had the same issue. I cleaned all the underwood connections I could find, as per yr suggestion, did a battery disconnect and thats kept it starting ever since, although it persisted with communication codes, until I spilled a coffee on the dash, and after taking the data port connector apart, discovered corrosion on the hot wire. That was last year, and its been running practically code free, till now. Does yr data port have some kind of short xtension on it? Mine does, thats where the problem was bare, but not now.
 

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2007 CTS 3.6 >131k miles
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701 Posts
Not that I'm aware of, but I didn't really look for anything on the port. I was getting an intermittent ABS code a few years ago and realized it was time to improve connectivity under the seats and elsewhere. I then disconnected everything I could find under the dash, under the hood, under the seats, and under the car, applied dielectric grease, and reconnected. Everything has been fine since (knock wood).
 

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2007 CTS
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211 Posts
Check the braided strap on the starter/solenoid. Mine decayed to dust. It caused intermittent starting issues before I discovered the prob.
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
Joined
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322 Posts
Discussion Starter #10
I got it! It was the positive terminal bolt. Bolt was tite, but cable end was just loose enough to have contact for dash lites, etc, but would not start car. Found a battery bolt that was threaded all the way, and that did it. Thanks guys! Maybe you mite check that out on yrs, Internetmechanicdegree? I don't know why they don't thread those stupid bolts far enough to pull the terminal in tight against the battery.
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
Joined
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322 Posts
Discussion Starter #11
Nm, still doing it. Seems like the battery disconnect fixes it for a little while.
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
Joined
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322 Posts
Discussion Starter #12
Yep, if I do a battery reconnect, it starts right up, and will for awhile.
 

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Registered
2007 CTS 3.6 >131k miles
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701 Posts
I suspect you have a bad ground connection. Or the starter cable as @Argent suggested. It would be best to do a voltage drop test, but in your case you already know that the positive cable has a connection issue. Therefore I would just replace both battery cables as a starting point. However if you are confident the cables are good, you could just clean the connection points with a wire brush and then apply dielectric grease.

Another possibility is the alternator. Unreliable charging can cause strange things to happen even though they do not appear to be related. For example, I was chasing an intermittent issue earlier this year, where the car would sometimes hesitate when taking off from a stop light, and would sometimes hesitate to start (cranked fine but the injectors did not seem to be pressurized unless I turned the key for a few seconds before cranking). I suspected a fuel pump issue, given that the battery and alternator were relatively new. However, the battery then started leaking, suggesting a charging issue. Further tests revealed the alternator was spiking to 16V occasionally and had apparently smoked the battery! I then returned the POS Carquest alternator* and replaced the battery under warranty. I then considered going with a new alternator but eventually settled on an ACDelco reman. This unit works perfectly and has never surged past 14.8 in any load condition (spec upper limit is 15.1). No problems since switching to a better alternator.

*Just for reference, my Carquest alternator experience may help others to avoid similar issues. I replaced the original unit two years ago with a Carquest reman. I based this decision on the lifetime warranty, versus the 2 yr warranty of other highly regarded brands (ACDelco, Denso). I installed the first unit and noticed a regular squeaking sound that was not caused by belt alignment. I then returned it for replacement and installed another unit. This time I experienced a consistent groaning sound. I then returned this unit for another replacement. Unit #3 was another squeaker, so I replaced it with #4. This time all seemed to be good, although I noticed it was slightly louder than the original. I decided to keep it, given that the R&R was not an easy task. Of course, by this point I had become proficient and was was able to finish the job in about 45 min! Fast forward a year and a half, and I started to experience the issue described above. The point here is to avoid store brand alternators at all cost! Stick to ACDelco or Denso.
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
Joined
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322 Posts
Discussion Starter #14
Thanks Ryan. I do believe the battery cables are OK. I wire brushed em with a cordless, when I changed battery, not too long ago. I had Jon mess with the double positive while I held the key over and also cycled the switch. Starts every time, after I take the neg cable off n reconnect to the battery. I always ck voltage, when I have issues like this. With hvac and lites off, it was 14.5, then down to 14.3. I did notice last week, when I was hitting the starter and solenoid with a hammer handle, it sounded kinda rattley. Especially the solenoid. I will hook up my meter today and look for voltage drop. Forgot bout that. Then drive up on blocks and ck out starter and wiring situation.
 

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2005 Base CTS work at Pullen solenoids Glass Factory for 36 and a half years
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175 Posts
If your cables are little loose on the battery post you can buy little caps at AutoZone and probably the other stores that you put over it then put your cable on and it will be a lot tighter.

Roy
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
Joined
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322 Posts
Discussion Starter #16
Hey TA Coupe, xactly what are you talking about? I dnt get it.
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
Joined
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322 Posts
Discussion Starter #17
I've ckd everything in sight, and cleaned terminals again. Just clicked this mrng, but am down to 2 codes. P0700 and U0100. Scan tool saz the 700 is from the U0100, which is loss of comm to the TCM. 700 turns on the CE lite. Did a quick reconnect of neg terminal, and it started right up, but CE lite was on and was getting very harsh shifts. Stopped, turned it off and on(it always restarts), no good. (Worked before) Cleared codes while driving and everything returned to normal. Even started at end of day, today. I'm thinking more that's its the ECM, its not communicating with the TCM. And when it fails to start in the morning, I dnt think the CE lite is on, till after I do the reconnect. I think the key- on CE lite is powered by the ECM. Ill see how it acts in the mrng. I still have to ck the trans plug at transmission, if I can get to it. Thanks guys.
 

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Registered
2007 CTS 3.6 >131k miles
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701 Posts
One more thing...kind of a long shot, last ditch effort, but you could try removing the PCM and blowing out the connectors with air, then reinstalling. A friend of a friend of a friend's cousin Vinny supposedly resurrected a clunker that way a few years ago. Could also try this with the TCM. Personally, I doubt it will fix anything but I can't imagine it will cause any problems.
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
Joined
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322 Posts
Discussion Starter #19
The TCM is on its side, just under and by the underwood fuse box. Is the ECM the thing mounted on the front of passenger side valve cover?
 
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